This paper reports the growth of octahedral magnetic Fe3O4 particles from iron powders via a simple alkaline hydrothermal process. The chemical compositions and morphologies of the as-grown Fe3O4 particles were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, and scanning electron microscopy （SEM）. Structure characterization showed that the phase structure of the prepared particles evolved from α-Fe to pure Fe3O4 with increasing concentration of KOH, indicating the important role of KOH concentration on the formation of the magnetite octahedron. The magnetic properties of samples were also studied by means of a vibrating sample magnetometer （VSM）. The pure magnetite Fe3O4 octahedrons exhibited a relatively high saturation magnetization of 96.7 emu/g.
Uniformly sized α-Fe2O3 hexagonal platelets were synthesized by a hydrothermal process using Fe（OH）3 suspension and large amount of NaOH. The reaction products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, selected area electron diffraction （SAED）, and a vibrating sample magnetometer （VSM）. The results show that the hexagonaq platelets are fine, monodisperse and consisting of single-crystals. The magnetic hysteresis （M-H） curvel of the samples measured at room temperature indicates that the α-Fe2O3 micro-platelets exhibit ferromagnetic behaviors with relatively low coercivity.
Dengfeng PengSadeh BeysenQiang LiYanfei SunLinyu Yang
